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Commission I: The silviculturists




O. MBURU (Kenya)

W.G. BARRET (Argentina)



W. KAUMAN (Australia)

Secretariat note


R. CATINOT (France)

Technical secretaries:



A.E. ALONZO (Argentina)

The days are over when the foresters could justly complain of being ignored by the general public. Following a quite natural reversal in trends, modern man, with his escapist tendencies, has now turned toward the forest, which he considers more and more his private domain, his place of recreation and rest, taking possession of it with the same haste that characterizes his life, and with the enthusiasm and preconceived ideas of a neophyte. For the very first time in history the forester is confronted squarely with the public, his new master from certain standpoints, often ignorant and sometimes aggressive, and if the forester is not careful it is he who will soon be told what a forest is and how it should be managed. Because the public is still ignorant of what a production forest really is, considering the forest merely a recreation park; it does not know that the state as owner imposes on foresters increasingly strict economic and financial constraints placing them before a dilemma: production or recreation?

This dilemma is more or less clearly enunciated in all papers received by this commission. It is the confession of that discreet and modest man-the forester- who suddenly finds himself struggling with greater responsibilities, all the more delicate because at first sight they appear irreconcilable. Is this not both too great an honour and too unlucky at the same time? Will he be able to come into his own, before some authority or new services restricts his activities or deprives of some of his prerogatives this man who knows all the problems and their possible solutions?

This, therefore, is the primordial problem that will surely crop up in many discussions during this congress: to gain recognition or to disappear.

Contrary to what happened at previous forestry congresses, the silviculturists' commission has attempted to synthesize for this congress all the current problems related to silviculture and forest management. This seemingly appealing formula entails some organizational drawbacks, so many and varied are the questions on this broad subject the world over. As a matter of fact in this summation we can only touch briefly on a few of the many interesting points raised in the papers submitted, for which brevity we apologize to the authors.

1. The silvicultural implications of changing demands upon forests and forestry

Foresters have often appeared to the outside world as persons living outside of time, who take no notice of its fleeting passage: because they must in faith believe that the future in which all their plans will be realized is not too distant from the present. Such was, indeed, the situation in recent decades, but great changes have taken place in the last few years and the traditional aim of producing very high-grade timber regardless of cost price or time involved has given way to the cost/return concept, or profitability. An immediate consequence has been the need to consider changes in demand: as foresters are now forced first of all to sell their product at a profit, they must be able to monitor consumer trends and, if possible, to foresee them. As a matter of fact, they have come to realize that, by keeping to the traditional properties for which wood was famous, they courted the risk of seeing its gradual substitution by other materials and displacement from the position it has held for centuries. And so, during the last few decades, foresters have begun to endeavour to produce as cheaply as possible fast-growing species, whose light wood is well suited to the needs of modern wood-using industries, especially in the form of chips or fibres (paper pulp, boards). The growing importance of plantation forestry is evident in national planting programmes and forest development planning of many countries, because the needs of our consumer society tend ever more toward relatively short-lived but inexpensive materials.

On the other hand, the hectic life in close quarters of our modern society forces man to seek an escape and to find in nature and in wilderness the balance of life which he is in danger of losing. Like the sea and mountains, the quiet landscape of the forest, its pure air, its game, seem to be particularly appealing to man. And all of a sudden the forester, until now one of the very few able to enjoy and appreciate all these wonders, is again placed on a dais, in full view of a both critical and admiring public, charged with new and important responsibilities in this new myth baptized " the human environment."

These two new demand trends are carefully and ably analysed by various authors, from the point of view of their implications for forestry. Kühl reviews comprehensively the silvicultural implications of the increased demand for wood, with special regard to the demand of the pulp and paper industry: regional planning, choice of good land, mechanization, liaison with research, manpower training, special financing, these are the fields where the efforts of public or private foresters must be deployed.

For his part. Carneiro gives a good picture of the global implications of the new demands that the forester must face. His estimates permit a quantitative approach to new problems, such as noise abatement and minimum green space in urban zones. He advocates taking a strong stance against the insidious, but continuing, practice of gradually clearing more forests under the most varied pretexts.

According to Zobel, the output of the major traditional wood-producing countries will increase very little from now on, owing to the constraints imposed by increasing transportation distances and by environmental considerations. The age of the tropical countries is heralded, because they can produce rapidly the pulpwood for which there will be a steadily rising demand. But one must resist the temptation of oversimplification, of harvesting wood prematurely although its technological value is poor, of neglecting ecological studies before introducing new species, of designing projects of too narrow a scope.

On the basis of observations made in France and in Europe, Croisé thinks that in view of the growing demand for industrial wood and the shortage of forest labour, forestry should improve yields and new forests be established, nursery work, plantation and lumbering should be mechanized as much as possible (the cost of which could be substantially reduced by prior opening in forests of service paths permitting the passage of mechanized equipment), and finally, thinning should be effected only in stands set aside for production of high-grade timber.

This interesting theory of compartmentalization deserves a more detailed explanation, as it appears to relate as much to research as to operational practice.

Pruvost, approaching the problems posed by the demands of environment, recreation and hunting, examines the constraints they impose on forestry which, in addition, must supply an ever-increasing volume of wood. Reviewing the main situations likely to arise, he proposes solutions which are generally- a compromise between diverse and conflicting trends and argues that these opposing forces (of which foresters were already aware, though without the need to take them as greatly into account as they must today) can be accommodated by traditional forestry practices. Consequently there is no need to reopen a discussion on the forester's old duties and new responsibilities.

Beresford-Peirse reached the same conclusion, believing that, in spite of the constraints entailed by the multiple use of the forest, the world's forest potential could easily meet the growing demand for wood and that, although he may be compelled to seek the assistance of other specialists, the forester should more than ever hold a ranking position.

Finally, Akiyama stresses the implications for Japan of the multiple use of forests and mentions the well-known definition of a forest: " the greatest gift to mankind." This appears indeed to be one of the few points on which all men -especially city dwellers - can agree and foresters should show enough imagination to draw from it all the support they need.

2. Improving the of quick-growing man-made forests

The establishment of quick-growing man-made forests has three objectives: to satisfy the growing demand for industrial wood already dealt with at length; to produce timber or roundwood in areas where the natural regeneration of indigenous species is difficult; to reforest denuded sites or those not well suited to forest-bearing, such as arid zones. The problems which arise in this context may be grouped under two headings:


Henceforth this will depend on an increasingly precise knowledge of facts, the range of which is described by Karschon: ecophysiological research, both in phytotron trials and by other tests, as on transpiration, resistance to cold and drought, etc. made in-situ, tests in arboreta, replicated trials for elimination of species and provenances, growth trials, pilot plantations. For arid zones, with which he is especially familiar, he recommends that planting sites be chosen on the basis of preliminary soil moisture studies. The time may come when such studies will be made using infrared aerial photography, but for the time being they must especially take into account the natural vegetation. He stressed the need for deep and regular working of the soil during and after planting.

With Iyamabo we enter into the less humid ecological zones, the Sudan and Guinean zones of Africa. Although the selection of species is again based on ecological studies, site analysis need not be as thorough in these regions, as water is less of a limiting factor. However, the concern not to make any mistakes with regard to the economic value of the species introduced is quite rightly emphasized.

Lamb and Laffitte give us the benefit of their great experience in the introduction of fast-growing exotics into tropical Africa and America. This type of plantation is spreading rapidly; at present several tens of thousands of hectares are planted annually with pines (P. caribaea, P. oocarpa, P. patula, P. elliottii) and several hundred thousand hectares with eucalypts (E. saligna, E. grandis, E. citriodora, E. camaldulensis, etc.). Much research on ecology and genetic improvement has been in progress for the last ten years and the forest policies of some countries (such as Brazil, Chile, Cuba, Uruguay and Zambia) are partially based on the introduction of exotic species. Detailed information on this is provided in several special papers, particularly that of Golfari on the ecological behaviour of species introduced into Brazil.


Great progress has been achieved in this field, due, in general terms, to intensified cultural care coupled with genetic improvement of planting stock, as well as to a great number of techniques making it possible to plant trees under the best conditions of nutrition and growth (fertilization, associated crops, proper thinning practices, pruning, etc.). Morandini and Poduje give us some excellent examples of these practices and Mehdizadeh reports on experiments aimed at keeping moisture in the soil by petroleum mulch. It cannot be said that better working of the soil is appropriate only for arid zones, because experience shows that at low altitudes in the humid equatorial zone and under Mediterranean conditions it is also very effective. An exception might perhaps be made in the case of some high-altitude tropical countries (Madagascar, Pacific islands) where superficial manual working seems to be sufficient. This is undoubtedly attributable to the interrelationship between the moisture needs of the trees and evapotranspiration. On the other hand, Leonardis, reporting on Argentina's experience, insists that the improvement of silvicultural techniques must be combined with genetic improvement and fertilization.

However, any discussion of plantation forestry would be incomplete unless mention were made of thinning practices: Volkart, speaking in general terms, proposes that, in order to compare validly the different systems and their results, an attempt be made to standardize the criteria for the different operations (number of stems, basal area, dominant height, etc.). The problems of thinning combined with pruning can only be solved by experiments in situ; however, some general rules and a research methodology have taken shape and we may refer, among the most notable ones, to the correlated curve trend plots devised for pines in South Africa, which Marsh and Burgers describe in their paper. This research technique applied to other species (eucalyptus, teak) allows not only determination of the optimum frequency of thinning, but also estimation of the volume of wood to be expected from one or another type of thinning. Pushing their investigations even further, and on the basis of these results, South African foresters have built a computorized growth model which makes it possible to define the optimum parameters for three species of pine on three different sites. This worthy achievement is described by Cawse, du Toit and Will-cock and certainly deserves special mention. Carretero also reports an interesting thinning design for poplars in Argentina.

A great deal of specific data, contained in reports too numerous to mention, is given with regard to the productivity of pines, eucalypts, poplars and araucarias, and this confirms the great value of these species. The mean annual increment of pines ranges from 12 to 20 m³/ha, the current increment being as high as 30 m³ in some cases; eucalypts can achieve levels twice as high. Research is now in progress on the regeneration of such plantations (Morandini, Riedacker and Karschon), the longevity of eucalypt stumps and the best time for cutting back in order to obtain maximum productivity together with maximum longevity; as far as is known, eucalypt stumps must be replaced every three or four coppice rotations.

Thus our knowledge in the field of quick-growing plantations is becoming more specific and may enable us to face successfully the constantly growing demand for wood referred to by Sir Henry Beresford-Peirse. But there is one danger which Iyamabo strongly underlines: that of being tempted to plant trees just for the sake of planting -establishing eucalypt plantations, for instance, whose wood will never be suited for local use. Large-scale planting should always be preceded by sound technological and economic studies.

3. Trends and progress in new forest management and silvicultural techniques

Traditionally, two trends have been singled out in silviculture: one of them, precise, strict, analysing facts through figures, almost resembles a science; the other, based on biological observations, much more suited for the understanding of the thousands of subtle meanings suggested by ecology and more intuitive, is closer to an art. The mind is always aware of this distinction, as is evident in all the papers submitted to this congress.

But how long will this last? Under the impact of modern trends toward multiple use of the forest, the forest manager and the silviculturist must consider forest production in its widest possible sense, as a whole, and will perhaps cease to think on any level other than that of forest ecosystems, as soon as understanding of the latter's biology becomes more advanced. In other words, when the results of the observations made by the" forester-artist" can be explained, dissected, quantified, with reference to the ecosystem, it will be possible to give a scientific explanation of his art. It is only through the improvement of our knowledge of biology that the distinction between " art" and " science" can be made to fade away, but it will be a long time before all the secrets of plant and animal physiology are known to us.

However rapid this evolution may be, one cannot but be struck by the way modern foresters attempt to solve their new problems by relying increasingly on scientific data.


It is precisely for the purpose of taking into account these new and imperious demands of public opinion that Bukman and Newton recommend the improvement, based on recent research, of methods of stand regeneration which will not appear as shocking to the public as clear felling and which pay more attention to the aesthetic value of the forest. In fact, U.S. foresters have recently been under great pressure from public opinion. which they will have to appease by proving the scientific bases of the silvicultural methods applied: from these, it is only a step to reasoning based on ecosystems; and recalling the "Scio me nihil scire" of Socrates, Vyskot stressed the importance of the Unesco programme " Man and the Biosphere," which should permit the analysis of all the complex problems linked to the structure and functioning of forest ecosystems. Some forest managers echo this sentiment: Vorobiov reports that foresters in the U.S.S.R. are endeavouring to develop wood production while conserving all the aesthetic value and environmental protection potential of the forest. Kairiukstis describes the initial results of his research on increasing yields based on a special method of intensive thinning to enable spruce trees to capture optimum solar energy. Nedialkov describes a method of " ecological management" of forests, feeling that the principal factors involved in stand productivity are the type of ecological site and the type of forest. But is it not true that the study of ecosystems is based on studies of just these factors? The same echo from Morocco, where Destremeau and Lepoutre submit that the ecological definition of a site is too frequently based on criteria chosen a priori and try to determine the latter on the basis of a refined study of growth correlated with climatic data, to define the " blocking factors" (photo-period, radiations, atmospheric humidity, etc.). But is this not a part of plant physiology and does it not, after all, lead to the same end? Similar studies are in progress in tropical Africa and in Argentina (Ledesma and Boletta), while in order to solve important management problems in the U.S.S.R., Atrokhin proposes that climax stands be regarded as ecosystems and that ecology and mechanization be used in conjunction to solve special problems of forest management. Finally, Mikhailov's important study on Populus tremula in the U.S.S.R. constitutes an excellent example of the practical contributions of ecology.

When only the production of wood is contemplated, there is an increasing tendency to think in economic and financial terms in order to meet growing demand. In New Zealand, a new technique has been adopted for conifers (P. radiata), similar to that used for poplars, owing to the fact that the most valuable part of the tree is considered to be the bottom log (Fenton). Haig and Scott refer to the considerable expansion of mechanized planting methods in Canadian forestry, which greatly reduce the cost price; container planting is being widely adopted for the same reason (Cayford).

The forest manager's task is to integrate all these biological and technical data, the latter frequently being conditioned by the former. Fraser has given thought to this problem and has developed a model for the study of stimulation of growth of a forest crop. Solutions can only be partial for the time being because much biological data is still missing, but results are already evident in the fields of fertilization and plantation establishment. Could this be the formula of the future?

Until it is perfected, however, more conventional solutions must be found for management problems, which are being increasingly subjected to the stress of environmental considerations and to the pressure of public opinion. Foresters in New Zealand are still unable to persuade the public that the management of the vast stands of Nothofagus entails their partial conversion by planting of exotics (Thomson, Kirkland and Miers), while Canadian foresters are at present attempting to define a formula in Ontario that will take into account the constraints of protection of the environment, and Bulgarian foresters must attempt to solve the difficult technical problem of improving the production of their hardwood forests (Grouev, Marinov and Sirskov). Solving these problems is certainly difficult and will only be achieved with the passing of time and a good deal of patience with the public. Worth noting is another initiative, both original and timely: forest areas near large urban centres can serve as suitable sites for the disposal of sewage and garbage (Evans and Sopper).

Silvicultural and management practices in tropical forests are much less elaborate, owing to the floristic complexity of these forests, which results in great differences in the requirements of species, as has very often been pointed out. Has any progress been made since the Madrid congress? Yes, some, but in relation to the refinement of existing techniques rather than in the invention of new ones. In southeast Asia (West Malaysia, Forestry Department), natural regeneration still reigns supreme in the dipterocarp forests of Malaysia, where in the rich plain forests felling accompanied by the poisoning of undesirable dominant species suffices to give the existing natural undergrowth its chance (Malaysian uniform system), while in poorer areas supplementary planting is necessary. In Africa, only Ghana (Baidoe), and to a very limited extent Nigeria, employ natural regeneration (selection system), whereas all the French-speaking countries plant indigenous light-demanding species (Aucoumea, Limba, Triplochiton) or exotics (teak). Studies relative to the management of these forests are still in progress, as the existing basic data are still insufficient. The need for the expansion of biological and forestry research is more urgent in this climatic zone than in others.

In tropical America, the experiments in the province of Tucumán (Argentina) reported by Posse show that natural regeneration is achieved only in a very limited measure and that it is necessary to resort to supplementary ball planting, the results of which are as yet uncertain. The silvicultural features of this continent seem, therefore, to resemble those of Africa.


The biological contribution of genetic improvement has led to notable advances in world forestry, and foresters rely on it increasingly (sometimes to an exaggerated extent) to meet the growing demand for wood.

Although we may deplore the small contribution made by geneticists to this congress, all of us are aware of the great work they have undertaken to increase stand productivity. Most countries now have a forest genetics service, in some cases with excellent facilities; in Cuba, where there are at present 1000 hectares of seed stands of Pinus caribaea, a great many phenotypes have been selected and the seed production zones classified according to ecological factors (Betancourt and Gonzales). This example appears to be specially typical of the efforts made by tropical countries in a field in which, ten years ago, they were lagging far behind. Certainly, they have been aided by international organizations and bilateral programmes: FAO, Australia, Denmark, France, Mexico and the United Kingdom have organized systematic collection of certified seed to allow for comparative provenance trials with the most promising tropical or Mediterranean species (pines, eucalypts, teak, Terminalia, Aucoumea, etc.). The efficiency of projects in this field carried out through international solidarity is worthy of commendation, as they make it possible to base research on genetic improvement on a satisfactory foundation, without errors arising from haste. It is necessary, though, to have the patience to go through all the required steps, by now well defined, and Mendonza develops this point in his paper on the urgent need for genetic improvement in Latin America, for which he sets the goals and incentives. Nikles and Reilly provide extremely useful information on the work carried out with Araucaria cunninghamii in Queensland (Australia) and on the results obtained; Peter and Squillace, studying the foxtailing of Pinus elliottii, reach the conclusion that further research will be necessary if the elimination of this phenomenon is to be achieved without losing other valuable inherited traits. Finally, a wealth of information can be found in several special papers on research in progress in India, Congo, Cuba, etc., which show the vigour of current genetic improvement work in the tropics.

For countries where genetic research is much more advanced, Grose discusses the best means of increasing its efficiency. He considers that all too frequently there is a gap between the level of tree-breeding work and the cultural treatments which could lead to optimizing yields. These two lines of research are all too frequently developed without the close link-up which would make it possible to study their correlation, so obviously valuable in boosting plantation productivity. The centralization of research services would seem to constitute the best solution.


Somewhat sceptically received at first by foresters, fertilization has since achieved status. It is this practice which gives plants the initial push they need on poor soils baptized, by reflex, "forest lands," and enables them to defend themselves, after planting, against parasites and competing weeds. Differences of opinion prevail among agronomists on the subject of the detection of soil deficiencies, some believing in foliar or sap analysis and some being partisans of " vegetation pots." Correction methods and the interaction of elements is another subject of discussion. Fertilization techniques are still in the infancy stage.

Another subject which merits reflection is the identification of those stages in the life of a tree when the application of fertilizers is most effective. A preference for the " starter-effect" has existed for a long time, but it was soon noted that the residual effect was weak and the impact of later applications has therefore been studied. At present attempts are being made to combine fertilization with thinning to ensure the dominance of certain trees (Rennie, Canada), but it is obvious that, although the formulas and techniques of fertilization can be left to the imagination of research workers, experiments must be made in situ with plenty of resources (statistical design, many repetitions), such as those described by Bonneau in regard to the experiments on Douglas fir (Pseudotsuga menziesii) made in France. Walker reports on the expansion of forest fertilization in North America, especially in pulpwood plantations, where N has a very marked effect when combined in various ratios with P and K, and on recent studies showing that clear felling sets off serious soil nitrogen and cation leaching. Szujecki feels that the destructiveness of this type of felling is specially harmful to the entomological fauna in the soil. It is certain that all substantial changes in the forest cover, whether due to the elimination or to the substitution of species, considerably alter all soil parameters, be they physical, chemical or biological (Velasco de Pedro). Tropical soils, which have in Acacia albida a remarkable forest fertilizing species (Giffard), are frequently poor in P2 O5 and respond well to fertilizers. Awan et al. give some good examples of the soil-vegetation relationship in Cuba.

In a paper which, to all intents and purposes, synthesizes all these topics, Maki attempts to define the optimal impact of fertilizers, in both time and space, within the framework of the great economic and social prospects for the future: fertilization is a technical as well as an economic and financial problem. The author stresses the decisive role of fertilization in helping foresters to meet the ever-growing challenge: continual increase in forest production on ever smaller forest areas. This can only be achieved by a substantial increase in yield per unit area, which requires constant application of fertilizers.


The product of a purely statistical calculation, forest inventories are already one of the basic tools of the forest manager, whether to describe an unknown forest, or to keep a finger on the pulse of managed stands. Aerial photography and, whenever possible, photo-interpretation are used to analyse basic data; colour emulsion and photo-radar already render useful services. But ground control is still indispensable. especially in the tropics, and Marmol describes the recent inventory made in the northwest of Argentina. Is the earth control satellite the harbinger of another step forward in our techniques?

On the ground, the forest manager uses volume tables and form coefficients, the new formulas for which are given, but he also uses mensuration devices which are constantly being improved, such as Bitterlich's tele-relascope, which we may have an opportunity to see in operation in Buenos Aires.

4. The present and future of tropical rain forests

Tropical forests represent over 60 percent of world forests and tropical rain forests cover 750 million hectares: this indicates their importance in global timber reserves. The interest attached to them by the general public in the past few years is due to the rapid development of the production of tropical timbers which, in 1971, were worth around two thousand million dollars. and to their still somewhat mysterious nature. For specialists and scientists, their enormous interest for the conservation of soil fertility is an added attraction, as well as a subject of study in view of the fact that all biological phenomena are more intensive and evolve faster there than anywhere else. Finally, like forests anywhere else in the world, they have a considerable environmental value.

In his general paper, Veruete-Fuentes recalls the essential figures that describe the biological, economic, financial and human potential represented by the world's tropical forests. While emphasizing the fact that their day has arrived, he examines the main problems involved in their development: frequently poor accessibility, shifting cultivation which nibbles them away, felling often with little or bad control, fire, pests and diseases. He cannot suggest suitable remedies in all cases, but stresses the great efforts needed in the field of silviculture.

Approaching the problem from a different angle, that of tropical ecosystems and the limitations on their manipulation, Catinot notes in the first place that as knowledge of these ecosystems advances, a certain disappointment is felt. so complex is their study and so modest their wood production: 400 m³/ha of biological production versus only 5 to 50 m³/ha of commercial timber. He stresses the fact, however, that they are usually neither managed nor improved by man and believes that when this is done their productivity will not only be comparable to that in other parts of the world, but much more quickly reach its top level. Unfortunately, the manipulation of tropical forest ecosystems is a very complex matter and so far results can only be obtained after their complete destruction (plantations of pines, eucalypts, gmelina, teak). The planting of other species is much more difficult and also requires the progressive destruction of the primeval ecosystem, while natural regeneration only gives good results in southeast Asia thanks to the plastic behaviour of a group of dipterocarps (Malaysian uniform system) or sometimes simply the release of desirable species from the new growth. Their conversion into farm land also poses serious difficulties, due to the rapid sterilization of the soil under clean (weeded) crops, and this in turn encourages devastating shifting cultivation.

While studying tropical forest ecosystems from the point of view of the environment, Lamprecht reaches the same conclusions: between shifting cultivation and the failure to regenerate stands, which are considered simply as resources to be mined, tropical forests are running the risk of a quick death, despite their enormous importance in the conservation of water, soil and life itself. To illustrate his point, he has chosen a number of specially conclusive studies based on calcutions showing the indisputably good effect on soils of the protection afforded by tropical forest stands, and he concludes with a cry of alarm: in many parts of the tropics, wooded land is still considered an obstacle to the march of modern civilization. economically speaking more harmful than useful. If this trend is not vigorously combated. we shall see the progressive and inexorable destruction of tropical forests, endangering the future of mankind in the tropics.

But how can ecosystems be better used from the economic point of view, ask Kauman and Kloot. There are no general rules, but only that of basing each case on research and studies applicable to tropical problems in developing countries, simply seeking. as in politics. The " art of the possible." but employing all the necessary means (good quality products, grouping of species for marketing, etc.).

If foresters and biologists can hope to have substantial research facilities at their command during the coming decade. before the destruction of tropical forests goes beyond the point of no return. it may be possible, in times to come, to make full use of the remarkable energy potential of these ecosystems. A deadly race is in course: will it be possible to stop the destruction of the tropical rain forests in time, before mankind has learned to manipulate and manage them?

5. The impact of silvicultural practices on the human environment

Suddenly confronted with new responsibilities related to the environment, the forester is forced to react. His technique-his art, as some say-forged by former generations, can be adapted to the new demands, all the more pressing because they are taken up and magnified by all the modern media of expression of public opinion: the forester finally comes out of oblivion, but only to hear himself too frequently criticized for failing to follow in the footsteps of his predecessor, he who was always criticized in principle for being too traditionalist. Attacked on two fronts-a rapid increase in productivity and the maintenance of a forest environment for recreation, leisure and beauty-the forester is faced with a dilemma which cannot be solved by simplistic and generalized formulas, as some superficially-minded people seem to think. For the time being, the public only sees and appreciates the forest landscape, which appeals to it, and all too often forgets that it was created by foresters, lovers of that very nature which was once ignored by the world at large; it disregards, on the other hand, the economic constraints with which the forester is confronted, arising out of both his concern for the public good and the economic planning of his government. Everything happens at once and something must be done quickly. Can forestry confront all the problems, with the aid of available techniques?

In his probing study of this acute problem as it occurs in the United States, Farnsworth examines the impact of forests on mankind, from the economic and material as well as the emotional point of view. The public is wearing blinkers for the time being, reacting only after the forest is actually destroyed or if the view or distraction it provides is too monotonous; a priori, though, there are many elements of judgement at its command. The public should be made aware of these elements, if only to force it to admit-as suggested by Samuelson- that even in clear-cut areas, constant changes accompany the gradual recovery of the young forest, which should be very attractive to the real lovers of nature. Is it necessary to recall, as Bourgenot points out, that some of the forests which now delight the eye of the tourist were created by artificial planting after clear felling, or, as Giordano says, that one is often very happy to have exotics available in order to protect natural forest ecosystems? It would be preposterous to suddenly abandon proven forestry practices; for the forester, a dynamic attitude signifies taking advantage of the growing interest of the public in the forest environment, in order to educate it and to imbue it with his ideas and perhaps his traditions, and to make it understand, for instance, that natural regeneration cannot solve all the problems.

The positive aspect of which the forester can now take advantage is stressed by Orrom and Mitchell who, after mentioning the aesthetic value of many forests brought under management in the past, submit their suggestions for the improvement of forest " vistas," especially at the edges of the forest and from certain viewpoints. The constant concern is apparent: not to deviate too greatly from conventional forestry techniques, but to study particularly the conversion of small areas, the "points of detail" which can do so much with so little. On another level, Aulitzky draws our attention to the importance of reforestation at high altitudes, which in the alps is of considerable interest from the point of view of tourism; such operations have only been made possible by the " ecogramme" method, derived from complex interdisciplinary research based on both ecology and physiology.


Fire has been used since prehistoric times, as it was for long man's sole effective means of handling the forest. While foresters as a whole cannot deny its deleterious and destructive aspects, their approach is gradually changing and now, though timidly, this factor begins to be part and parcel of management practices. If Gaillard's study is more oriented toward the rational organization of control methods, even at the international level, McArthur draws our attention to the fact that fire is a natural component of many forest ecosystems and that its disappearance from these forests may disrupt the ecological balance, provided it is not too strong a constraint on the human environment. De Rada and other authors refer particularly to its negative aspects, if only in connexion with the present fashion for "recreation forests," where the education of the public is of primary importance. Taking up Gaillard's argument, Macleod too considers the matter serious enough to warrant international cooperation. In fact, our approach should be much more flexible: whereas in certain ecological zones early fires are permissible or even useful, in most Mediterranean and softwood forests fire is a scourge which permits no compromise and which must be fought by the most powerful means.


Attacks by parasites constitute as great a danger to forests and their future and one that is probably as difficult to combat as fire, because, as Grison remarks, the eradication of a single species by chemical means is illusory. There is no ecological synthesis at the species level, but only at the biocenosis level; thus only integrated control can be really effective. In fact, he says, " at a given point, the density of a pest population results from the hostile action of two groups of factors: the multiplication potential of the species versus the resistance of the environment." It is therefore necessary to take both into account simultaneously and this involves, in particular, the " manipulation of the environment," i.e. the work of the forester who must make joint cause with the zoologist. Koehler describes the application of these principles to parasite infestation in plantations, where the measures taken involve even the artificial feeding of entomophagous species and the establishment of integrated control centres. This very complex approach to control may be the formula of the future, although there can be no question of abandoning chemical weapons quickly, as Tarrant, Waters and Gratkowski contend, considering it possible to adapt chemical control to mankind's new concern about technological and environment matters. Fettes and Buckner confirm this in their study on the control of spruce Choristoneura in Canada: while it was necessary to abandon DDT as harmful to the environment, another less aggressive chemical product is now being used; furthermore, an ever greater effort is being made to combine chemical and biological control, in order to afford the environment as much protection as possible.

To conclude, what can we do but hope that with a little skill and a great deal of knowledge the forester will be able to make the public accept his traditional practices, so adjusted as to take into account the simultaneous demands of both production and recreation?

Imagination and dynamic action should be able to meet the new demands.


The papers submitted by the foresters who have contributed so generously to this congress have strengthened our belief that their hour has come. Everything seems to contribute: the frenzy about the environment, the pessimistic comments on the future of the world's nonrenewable resources, the foresters' great and long-acquired knowledge of an ecosystem of which only the name and the modern synthetic conception are novel to them. By what right should one pretend to remove them from a domain where they usually feel as much at home as do scientists, from whom they can often be distinguished only by different terminology and turn of thought?

Nevertheless, foresters should beware of two temptations: to disregard the problems posed by public opinion, because they can either discreetly prove their inanity or attempt to solve them; and to disregard the potentials of the continuing evolution of scientific research in both biology and mathematics. Such research is the basis on which they will improve their techniques and construct their explanations which, if clearly stated, should convince public opinion. They must go beyond the stage of detailed observation and of intuition, in which they have excelled for centuries, and realize that it is now their duty and interest to look at the phenomenon from the inside on the basis of the substantial pragmatic knowledge they have been able to accumulate. It does not matter whether they join forces with scientific research workers or have some of their own profession specialize in research, but it is essential that they make themselves heard and command respect at all levels of discussion and controversy; otherwise they will find themselves caught in a vice between public opinion on the one hand and scientific opinion on the other. Their principal goal should be to select practical patterns of action, solidly supported by irrefutable scientific findings, leaving to others the joy of handling the purely intellectual concepts that generate great scientific discoveries.

As needs develop, both for the world's renewable resources and for the resources giving balance to life which mankind will increasingly seek, foresters should emerge from the obscure position which has traditionally been assigned to them and rise to the same level as that of the specialists most in fashion.

But this cannot be achieved without an effort of imagination and will and application to the improvement of existing knowledge, often on a new plane-an effort which should not fail to appeal to the new generations and thus attract more recruits to one of the world's most balanced professions.

Commission I papers


Akiyama, T.

The silvicultural implications of the changing demands upon the forests and forestry

Atrokhin, V.G.

The rational system of special purpose stand forming in managed forest compartments

Aulitzky, H.

Biological research in the sub-alpine area. The basis of reforestation activities with the objective of biological control of avalanches

Beresford-Peirse, Sir Henry.

The challenge of the growing demand for wood and wood fibre

Buckman, R.E. & Newton, M.

Principles of silviculture. Current trends and their significance

Carneiro, N.

Las implicaciones pare la silvicultura originadas por los cambios actuales de la demanda sobre los bosques en particular y la forestación en general

Catinot, R.

Possibilitiés biologiques et économiques des écosystèmes forestiers tropicaux et les limites de leur transformation

de Rada, R.

Los incendios forestales y su relación con la recreación y el turismo

Evans, J.O. & Sopper, W.E.

Forest areas for disposal of municipal, agricultural and industrial wastes

Farnsworth, L.E.

Impact of silvicultural practices on man

Fenton, R.

New approaches in softwood silviculture

Fettes, J.J. & Buckner, C.H.

Biocides in the forest: use and misuse

Fraser, A.I.

A technique for improving the flexibility of silvicultural practice in relation to the management of man-made forests

Gaillard, J.B.

La prevención y lucha contra incendios forestales como parse indivisible de todo manejo silvícola

Giordano, E.

L'emploi des espèces forestières exotiques pour la protection des écosystèmes forestiers naturels et pour la defense et la reconstitution du sol

Grison, P.

Lutte intégrée en milieu forestier

Grose, R.J.

Combining genetic improvement and cultural measures to increase productivity in intensively managed forests

Iyamabo, D.

Trends in the choice of species in afforestation

Karschon, R.

Trends in the choice of species in afforestation when moisture is a limiting factor

Kauman, W. & Kloot, H.

A strategy for utilizing the potential of multi-specific forests

Koehler, W.

The patch-complex method of forest protection

Kühl, G.

Las implicaciones pare la silvicultura originadas por los cambios actuales de la demanda sobre los bosques en particular y la forestación en general

Laffitte, J.C.

Los silvicultores y la forestación con especies exóticas en América Latina

Lamb, A.F.

Tropical pulp and timber plantations

Lamprecht, H.

La importancia del bosque tropical, vista en el contexto general de las relaciones ecólogico-ambientales de los bosques

Leonardis, R.F.J.

El mejoramiento de la producción de los bosques artificiales de crecimiento rápido. Mejora de los tratamientos silvícolas

Macleod, J.C.

Forest fire control: - an opportunity for international cooperation

Maki, T.E.

Dependence of forest and wood production on fertilizers

McArthur, A.G.

Fire as a tool in forest management: the new constraints arising from the conservation of the human environment

Mendonza, L

Mejoramiento genético de las especies forestales: una necesidad impostergable en América Latina

Morandini, R.

Sylviculture des forêts artificielles

Orrom, M.H. & Mitchell, A.F.

Silviculture and good landscapes in British forestry. The improvement of planning and practice

Poduje , L.

Bosques artificiales de crecimiento rápido en las zonas semiáridas. Tratamientos silvícolas

Pruvost, P.

Les problèmes dérivant de la demande croissante pour les produits et services autres que le bois

Tarrant, R.F., Waters, W.E. & Gratkowski, H.J.

The future role of chemicals in forestry

Thomson A.P., Kirkland A. & Miers, K.H.

Multiple use management of temperate hardwood forests

Veruete Fuentes, J.

Presente y futuro de las selvas cálido- húmedas

Volkart, C.M.

Revisión de expresiones de densidad de mesa aplicables en las prescripciones de raleo

Vorobiov, V.G.

Main trends in forest utilization and forest management in USSR

West Malaysia. Forestry Department.

Trends in the controversy of shelter wood systems, with particular reference to West Malaysia

Zobel, B.

Iudustry's increasing and changing requirements for wood


Abell, T.M.

The establishment and silviculture of pines in Zambia

Arevalo Carretero, C.

Utilización del contrafuego en los incendios forestales

Arreghini, R.I.

Tratamiento previo a la siembra de semillas de Caldén (Prosopis caldenia Burkart)

Atuahene, S.K.

The major etiological problems facing Ghana's reforestation programme

Awan, A.B. et al.

Condiciones del suelo que afectan el desarrollo y crecimiento del pino en Cuba

Baidoe, J.F.

The management of the natural forests of Ghana

Bakarcic, M.

Cercosporiosis en las hojas de sauces en el delta del Paraná

Barrena, G.

Nuevo método para determinar coeficientes mórficos

Betancourt, A. & Gonzales, A.

Trabajos realizados en Cuba sobre mejoramiento genético de Pinus caribaea Morelet var. caribaea Barrett y Golfari

Bhatnagar, H.P. & Joshi, D.N.

Rooting response of branch cuttings of teak (tectona grandis L.F.)

Binmore, A.

An outline of problems arising in the replanting of clear-felled Eucalyptus stands in Zambia

Bohórquez Rejas, A.J.

El Eucalyptus globulus Labill. Regeneración natural, producción y costos en el valle del río Mantaro (Perú)

Bonneau, M.

Quelques résultats d'essais de fertilisation sur Douglas (Pseudotsuga menziesii) dans l'ouest du Massif central

Bonnemann, A.

Modificaciones de las propiedades de las maderas como consecuencia de la transformación del bosque natural en bosque manejado en la región forestal de Chile

Bryan, L.W.

The genus Pinus in Hawaii

Burschel , P. et al.

Ensayos de reforestación por siembra directa en la zone de los bosques Magallánicos Caducifolios, Coyhaique, provincia de Aysen (Chile)

Carretero, R.V.

Contribución al estudio de un cultivo de álamo bajo riego en el valle de Tunuyán, provincia de Mendoza (Argentina)

Cawse, J. Du Toit, J. & Willcock, D.

Optimum pulpwood regimes for plantations of Pinus patula, P. taeda and P. elliottii

Cayford, J.

Trends in container planting in Canada

Cersosimo, F.J.

Ensayos con álamos en Santiago del Estero (Argentina)

Chinte, F.O.

Regeneration, growth and yield of Philippine dipterocarp forest

Chittaranjan, I.F.S.

Tracasserie in forestry

Christensen, H.G.

Site assessment research for pine and eucalyptus plantations in Zambia

Colcombert, J.L.M.J.

Un método de raleo para Araucarias en Misiones (Argentina)

Croise, R.

Tendances de la sylviculture en relation avec l'evolution générale de la foresterie

De Arruda Veiga, A.

Three technical systems used by the Forestry Institue of São Paulo (Brazil)

De Errasti, R.

Recuperación de bosques quemados

Del V. Martínez, E.

Impacto de las operaciones de des-embosque en el ambiente humano y sus interrelaciones con los tratamientos silvícolas

Destremau, D. & Lepoutre, B.

La détermination des facteurs climatiques limitant la croissance chez quelques essences de climat méditerranéen. Son importance écologique

Ferreira Dos Santos de Azevedo, N.

About Armillaria mellea (fr.) Kummen Selecting root-rot resistant Cryptomeria

Forster, R.B. & Simard, AJ.

Tactics of using aircraft for forest fire suppression

Freitas, E.R., Ferreira, N. & Borges, C.

Study on the botanical variations in plantations of Eucalyptus alba Reinw., E. saligna Smith, E. grandis Hill ex Maiden, E. propinqua Deane and Maiden

Fuentes, J.M.

Interaction between planting-site and seed-source in Loblolly pine

Gartland, H.M.

Aspectos estáticos de la regeneración de los bosques de Misiones (Argentina)

Giffard, P.L.

Role de l'Acacia albida dans la régeneration des sols en zones tropicales arides

Gilmour, J. R. & Glew, D.R.

Silviculture in British Columbia

Giunchi, A.J.

Los álamos y la salinidad de los suelos

Golfari, L.

Impacto de la ecología en la elección de las especies para la forestación

Gómez Ricaño, J. R.

Zonificación de áreas semilleras en Cuba

Gonzalez, R.A.

Crecimiento de Pinus taeda en la provincia de Misiones (Argentina). Influencia de la calidad de la semilla en la producción maderera

Grouev, I., Marinov, M. & Sirakov, C.

Amelioration de la composition et de la productivité des forêts feuillues en République populaire de Bulgarie

Guldager, P.

Method for seed grading and seed issues for direct sowing in pots

Gurgel Filho, O.A. & Gurgel, J.T.A.

Ecotypes in Brazilian pine (Araucaria angustifolia [Bert] O. Ktze)

Haig, R.A. & Scott, J.D.

Mechanized silviculture in Canada

Hawkins, P.J., Nikles, D.G. & Smith, W.J.

Management, genetic improvement and wood properties of Pinus caribaea Mor. in Queensland

Hoepke, E.

La Patagonia. Forestar es poblar

Kairiukstis, L.

Scientific principles and practical methods of tending fellings and unclear cuttings in storeyed stands of the north-western part of the U.S.S.R.

Karschon, R.

The course of coppice regeneration of Eucalyptus camaldulensis Dehn

Khan, M.I.R. & Khanzada, S.K.

Raising of fast-growing species in West Pakistan

Kram, O.N. & Martínez, L.

Plantaciones industriales con pino en Ia provincia de Tucumán (Argentina)

Kronka, F.J.N. & Chagas Campos, J.C.

Tabla de volumen comercial para Pinus elliottii Engelm.

Le Blanc, H.

De la théorie á l'application de la sylviculture, en pineraie grise

Ledesma, N.R. & Boletta, P.E.

Clima de las regiones forestales argentinas

Lisbao, L. Jr. & Suiter Filho, W.

Preservation of seeds Eucalyptus saligna in several levels of relative humidity

Luna Flores, C.D.

Análisis foliar de Eucalyptus botryoides con abono mineral en su crecimiento inicial

Luna Flores, C.D.

Efecto del uso de fertilizantes en su crecimiento inicial de Eucalyptus botryoides

Marmol, L.A.

Inventario forestal de los bosques del noroeste de la Argentina

Marsh, E.K. & Burgers, T.F.

The response of even-aged pine stands to thinning

Martin, B.

Perspectives d'industrialisation papetière au Congo-Brazzaville. Problèmes de multiplication d'un hybride d'Eucalyptus a haut rendement

Martínez Miranda, O.

Ensayo sobre la influencia de la fertilización y densidad de siembra en la producción de plantas de Pseudotsuga menziesii Mirb. Franco

Matos González, E.

Análisis de crecimientos en diámetros, alturas, áreas basales y volúmenes del Pinus caribaea Morelet var. caribaea Barrett y Golfari en algunas plantaciones realizadas en Cuba

Mehdizadeh, P.

Petroleum mulch. Its use in insulating soil surface to increase water availability in dry afforestation in arid and semi-arid zones of Iran

Miglioli, J.A. & Rozados, J.J.

lnforme sobre crecimientos observados en coníferas exóticas en la zone cordillerana del noroeste de la provincia de Chubut (Argentina)

Mikhailov, L.E.

Aspen stands in central Russia and the ways to their improvement

Molino, O.

Rendimpiento de pings resinos a distintas distancias de plantación

Molino, O. & Vairetti, M.

Crecimiento de pings resinos en el norte de Corrientes comparado con Misiones (Argentina)

Mullin, R.E

Effects of cultivation after planting in establishment of white spruce plantations

Nedialkov, S.T.

Méthode écologique d'aménagement forestier

Nikles, D.G. & Reilly, J.J.

Management and genetic improvement of the native Araucaria cunninghamii Ait. in Queensland

Pederick, L.A.

An analysis of seed production of 15 clones in a Pinus radiata seed orchard

Pelov, A.

Amelioration de la composition et de la productivité des forêts feuillues en République populaire de Bulgarie

Peter, J.K. & Squillace, A.E.

Genetic effects, chemistry, and foxtail growth patterns in Pinus elliotii

Posse, R.M.

Métodos silviculturales de enriquecimiento del bosque subtropical en la provincia de Tucumán (Argentina)

Prego, A.J. et al.

Plantación de álamos y sauces pare establizar médanos

Rajhkowa, S.

The present and future of the tropical rain forests, with special reference to India

Rennie, PJ.

Forest fertilization in Canada

Riedacker, A.

Physiologie des souches d'Eucalyptus camaldulensis traitées en taillis au Maroc. Le problème de leur vieillissement

Rojas Valero, E.

Los chopos en la provincia de Granada (España)

Ross Grinnel, W.

Silviculture in Ontario

Rozados, J.J. & Miglioli, J.A.

Evaluación del crecimiento del ciprés

de la cordillera (Libocedrus chilensis) sobre las costas del lago Epuyen (provincia de Chubut, Argentina)

Samuelson, E.

Silvicultural practices and the human environment in Sweden

Shimoya, C. & Zunti, A.C.

Anatomy of the tuberosity in the region of the connecting point of root-stem of Eucalyptus spp.

Shimoya, C. & Zunti, A.C.

Precaution in development's phase of the homeoplastic graft, top forkage type, in Eucalyptus saligna Smith

Spencer. R.D.

Supplementary aerial photography

Strezelecki, W.

The effect of various treatments on the silvicultural value of pine plantations on sand dunes

Suiter Filho W. & Barboza Leite N.

Some aspects of the vegetative propagation of Eucalyptus saligna Smith by grafting

Szujecki, A.

impact of clear cutting on the soil entomofauna

Taveira Fernandes, C., Godinho, J.C. & Pinto de Abreu, C.A.

Le chataignier et le noyer. Possibilités comme espèces forestières au Portugal

Tesdorff, H.N.F.

Ensayo de cruzamientos de Araucaria araucana K. Koch y A. angustifolia (Bertoloni) O. Ktze.

Vairetti, M. & Molfiho, A.

Crecimientos de álamos en Misiones(Argentina)

Vega Condori R.

Las formas fisiográficas en el mapeamiento y evaluación de los "Cerrados"

Veiga, R.A. & Carvalho, C.M.

Volume equations for Eucalyptus saligna Smith

Velasco de Pedro F.

Influencia de la roturación en la repoblación forestal sobre diversas propiedades físicas del suelo

Versepuy, M.M.

Nouvelle technique d'enrobage biologique garanti sans aucun produit toxique

Victor, M.A M. Yamazoe G & Gurgel Filho, O.A.

Investigación y experimentación con Paulownia spp. en el estado de São Paulo (Brasil)

Villaescusa Sanz, R.

Logística de los trabajos de campo del inventario forestal nacional

Villanueva Aranguren, J.A.

Un estudio sobre el posible sesgo en la utilización del relascopio como estimador de áreas basimétricas

Vyskot, M.

New trends in the science of silviculture

Walker, C.

Forest fertilization in North America

Zunti, A.C. et al.

Anatomic study of welding of top grafting in Eucalyptus saligna Smith


The silvicultural implications of the changing demands upon forest and forestry

1. The two contrasting trends with which the forester is now confronted, reflecting the need for (a) more wood, especially for industrial purposes, and (b) more forest land for the conservation of the environment and for recreation, though recognized already by the fifth World Forestry Congress in Seattle, have taken shape only since the sixth congress in Madrid. Concern for the environment especially has spread enormously over the last six years and now constitutes a major preoccupation of foresters in some of the more densely populated countries.

2. High-yielding man-made forests of fast-growing species can expeditiously meet the increasing demand for industrial wood. But in order to produce such wood competitively, the right species must be planted on the right site; the establishment and tending operations must be refined and rationalized, and also mechanized to the extent that the social and economic environment permit; logging and marketing requirements must be taken into account from the very moment the establishment plan is conceived. However, the role that dry forests in temperate regions and open woodlands in tropical areas can play to meet locally increasing demand should not be neglected.

3. All measures should be taken to make the fullest possible use of forest raw material in order to prevent future wood shortages.

4. In line with the concern for the environment, silvicultural practices need to be pragmatically retailored, including the demarcation of certain areas of the forests, to be managed and equipped so that they can best meet recreation requirements. Short-term economic considerations should not be allowed to outweigh longer-term social and biological considerations.

5. Irrespective of the objectives of management, including the protection of nature and of the environment, the forest needs to be tended if it is to survive. This is the forester's, especially the silviculturist's, duty and privilege. Therefore he should have a predominant role in the decision-making and practice of forestry, with the advice and assistance of other specialists when needed.

6. There is the case of " wilderness preservation" where no intervention of any type is permitted, the emphasis being on the preservation of gene resources and the " nonwood values" of forestry. In many countries there is insufficient forest land available to lock up large areas completely without managing them. Rural employment has to take precedence over complete conservation, but under rational management there is no reason why the gene resources cannot be preserved, and there need be no conflict of interest.

Improving the yield of quick-growing man-made forests

7 Man-made forests of quick-growing species contribute greatly to the production of industrial wood in humid areas. In arid zones the plantation forest is often the only source of domestic supply of timber and roundwood, as well as a protection against soil erosion of cultivated land. The rates of growth of irrigated plantations in these zones can be very high indeed. But long-term management still poses serious problems which call for continuing investigation.

8. The choice of species and site is important from the technical, financial as well as human point of view. Care must be taken not to be misled by a species which gives initially an apparent high level of production when, in fact, it is not entirely suited to the site in the long run.

9. The search for the optimal combination of species and site is never-ending. Forest tree improvement can render valuable service in this connexion, and the international assistance available in this field is to be particularly commended. There is need, however, for a better standardization of the methodology for species elimination and provenance tests, and in this the International Union of Forestry Research Organizations could play an important role.

10. The final choice of site depends as much on economic as on ecological factors, among which marketing is of paramount importance. Experience shows that all too often inadequate attention has been paid to this in the past, in developing as well as developed countries. There should be better coordination between forestry authorities and industries to plan siting of forests and factories, and to ensure a sustained flow of material.

11. The remarkable success obtained so far with manmade forests is due mainly to the intensification of cultural operations, both for establishment and tending, coupled with tree improvement and fertilization. Further progress depends on the acquisition of better knowledge with regard to the effect of spacing at any given age on the biological balance in the plantation, and on the quantity and quality of the total yield. Results from correlated curve trend plots in certain countries have provided valuable results already in this connexion, but the need for a refinement of the methodology is acute and standardization of thinning parameters would help a great deal to achieve a better understanding of the results obtained by various workers.

12. The deleterious effect of thinning operations, when they are not properly timed, should be kept in clear perspective with regard particularly to the possibility of enhanced damage by pests and diseases. This danger should never be underestimated in man-made forests, especially when genetic diversity within the plantation is small.

13. If rates of growth of man-made forests are such that their contribution can be highly significant to meeting the challenge of the increasing demand for wood for industrial and domestic purposes, it does not appear that present techniques will enable man-made forests to contribute as substantially to meeting the demand for large timber. Here is an area where considerably more effort needs to be deployed.

14. The establishment and management of man-made forests also provide social benefits, the value of which should be taken into account in justifying the relatively high initial cost. There should be more effort to quantify such benefits.

Trends and progress in new forest management and silvicultural techniques

15. Silviculture has traditionally tended to follow two divergent courses. On the one hand, strict analysis of facts through figures has almost become a science; on the other hand, practice based on biological observations, aimed at the understanding of complex situations, is more intuitive and almost resembles an art. This conceptional luxury can no longer be afforded. The entire forest production cycle must now be considered in its widest possible sense, and the impact of modern trends aiming at the multiple use of the forest should inevitably lead the forest manager and the silviculturist to think only in terms of the forest ecosystems. The distinction, however, between " art" and " science" can be made to fade away only if the understanding of the biology of forest ecosystems is considerably improved. It will still take time.

16. Man-made forestry and natural forestry both contribute to meet the rising demand for more diversified forest products and services. Both are needed, so there is no competition. However, they must adjust, especially in the more densely populated countries, to the new awareness of long-standing constraints caused by environmental concern. The adjustments needed range from supplementary silvicultural operations (pruning. thinning) to the replacement-if the prevailing ecological conditions permit-of the clear-felling system with other silvicultural systems slightly less efficient but still compatible with the silvic requirements of the tree species involved. At the same time, the establishment of " green belts" should be encouraged in the proximity of large towns, and tended and managed to cater particularly for the relaxation and amenity of those living under close urban conditions. Other experiments under way which are worthy of mention include utilizing the nutrients contained in municipal, agricultural and industrial wastes for the creation of forest areas near large urban centres. Care must, of course, be exercised to prevent the existing forests from becoming excessively inundated with such wastes.

17. The management of forest resources remains primarily a technical problem, despite the emotional repercussions it might entail and the consequent political pressure. Should emotions prevail, the future of the forest is doomed.

18. The use of mechanization is spreading widely both in the nursery and in the forest, but terrain conditions command respect as well as the need for minimizing the damage inflicted upon the environment.

19. The trend should be noted for the forester to rely increasingly on ecological and scientific data, ranging from the study of mathematical models to identify the best means to stimulate growth, to the execution of silvicultural operations aimed at enabling trees to capture optimum solar energy.

20. As for the natural regeneration of tropical forests, results have been reasonably satisfactory so far, for instance in the rich plain forests of southeast Asia. But other types of forests are still recalcitrant and this problem requires much further effort.

21. As mentioned earlier, tree improvement is instrumental in ensuring that more and better wood is made available at cheaper prices. Essential prerequisites to enable tree improvement to give its greatest benefit are to conserve the existing genetic diversity of tree species and to make as much genetic material available to foresters as possible. This will enable them to ascertain which genes best match the conditions of the sites for which they are responsible. The problem of collecting seed and making it available, or trading it, without losing track of the source, has been tackled both by the Organisation for Economic Cooperation and Development (OECD) and FAO) for commercial and research purposes respectively. Their effort is to be commended, but the problem is not going to be solved unless more countries adhere to the OECD scheme for the certification of forest seed moving in international trade, and unless other financial resources are made available to supplement the funds that FAO) has been able to provide until now to procure seed of important plantation species.

22. Fertilization may well become one of the forester's major weapons of the future, both in the nursery and in the field, but it has technical as well as economical and financial problems. A great amount of basic data to optimize its impact on forest productivity is still missing, and any effort to encourage investigations or exchange of information in this field should be particularly commended. Increases in yield due to improvement of form are particularly noteworthy.

The present and future of tropical rain forests

23. More than 60 percent of the world's forests are tropical, and tropical rain forests cover 750 million hectares. Their global and local importance from the economic and social point of view is indisputable. Their potential has long been described as enormous, but the problems they pose are still great, e.g. accessibility, heterogeneity, and protection.

24. Forestry exports from developing countries have tripled in recent years and their value is now of the order of almost $2 000 million. This seems often more than the tropical forest can locally sustain, most of the production coming from the richest areas, which are a small percentage of the total area. But, the role that tropical forest can play for soil and water conservation, that is for the conservation of life itself, is of very great importance.

25. Even though generally underutilized, unless the present mismanagement of the tropical forests in some areas is halted and reversed, their future may be short-lived. While it is recognized that some technical bases are still missing, it is the lack of financial resources and the relatively high cost of establishment which constitute the major stumbling blocks, and there is a reluctance of international financing organizations to entertain applications for regeneration purposes. The possibility should therefore be explored of reducing the pressure on the tropical rain forest by concentrating research on its rational utilization as well as by establishing manmade forests in the more open lands outside the tropical rain forest area. This should safeguard the threat to the existence of the natural rain forest and its environmental features, even though it is recognized that monoculture introduces the danger of bioinstability.

26. The ecological knowledge of the complex tropical forest ecosystem is inadequate, silviculture has not developed as it should and there is a low technology for local processing of forest products. Current production of wood in Africa is 5 to 50 m³/ha against a biological production of up to 400 m³/ha. These low production figures relate, however, to natural stands. and when these stands are changed to a modified type of mixed forests, or replaced artificially, their economic production should not only be comparable to that of forest ecosystems in other parts of the world, but should quickly reach its top level.

27 The technological properties of many tropical timbers are still insufficiently known, and possible markets are therefore lacking. Investigations should be pursued by research institutions, in close collaboration with those industries which ultimately have to put the wood to use. The great energy potential of tropical forest ecosystems should also not be overlooked.

The impact of silvicultural practices on the human environment

28. By definition, the work of the forester, more specifically of the silviculturist, affects the human environment. Since the very inception of this profession, the silviculturist has toiled to ensure that there would be forests on earth, generally with the total indifference or opposition of the public authorities and public opinion. Indifference has now changed into emotionalism and enthusiasm, but the forester's duty remains what it has been for centuries: to take care of the forest so that it shall not perish. Silvicultural techniques will have to be adjusted so as to attain the ultimate and most important objective without unduly affecting the environment, and without making the practice of forestry grossly unsound from the economic point of view. Refinement is what is wanted, in approach and execution, and not radical change.

29. Close as forestry and landscaping may seem to be, there are some substantial differences which should not be underestimated. It would help greatly to mitigate the controversy if what enhances and what is deleterious to the landscape were clearly determined, and if land were classified from the landscape point of view so that sensitive areas (e.g. woodland edges) might be identified and given careful treatment. It would also be useful, in order to reassure public opinion that sound forestry and good landscaping can coexist, to establish sample areas in public as well as private forests. of easy access to the general public, where information would be made available in the demonstration areas on the forestry activities carried out in the past. It should be emphasized that some of the forests now held in great esteem by nature lovers and the general public are, in point of fact, man-made. Natural regeneration is no panacea and cannot solve all problems; under certain conditions of accelerated degradation only exotic species may help to protect the natural ecosystem.

30. Fire has been man's companion, for better or for worse, almost ever since man appeared on earth. A small though increasing number of foresters is prepared to consider fire as an integral part of the forest ecosystem and as a tool for its management. However, its noxious and deleterious effects cannot be denied and fire control is imperative in many areas. It is to be hoped that funds will soon be made available to FAO) for the establishment of a forest fire technology unit, as recommended by the United Nations Conference on the Human Environment (Stockholm, 1972). At the same time, the possibility should be explored, by all the organizations concerned, of setting up an international commission on forest fire control.

31. Pests and diseases combine with fire to complete havoc. In the past, countermeasures have consisted mainly of direct attack by chemical means. It is now clear that this approach is not without risk, and can at times be dangerous to the ecosystem. All strategy in this field, to be successful, must be based on a preliminary study in depth of the interrelationships between the parasite, which generally has some built-in resistance of its own, and its environment. The answer seems to lie in a combined attack integrating all possible methods (chemical, biological, mechanical), which should lead to better control while minimizing damage to the ecosystem. It is also vital that chemical means be considerably improved through research and made as little harmful to the environment as is compatible with the maintenance of an acceptable degree of efficiency.


32. As forest managers, silviculturists are responsible for natural resources that are indefinitely renewable in character and constitute a reliable insurance for the future of the human world. Entrusted with the protection of hill land and catchment areas, and with the role of forestry in integrated land use, silviculturists are confronted more and more with a substantial and ever increasing demand for wood and forest products. They are also faced with the fact that man in industrial societies is now overwhelmingly attracted to forest land for recreation, leisure activities and aesthetic enjoyment, and with the consequent pressure for the conservation of the natural environment. Silviculturists are determined to face all these demands and declare their continued competence in the management of forests and forest land for multiple use, with the assistance of specialists in other fields in case of need. They are convinced that their vocation, backed moreover by a widely-based education, training and experience in biology, economics and mathematics, represents the best safeguard for the management and conservation of renewable natural resources in general, and believe it imperative that they should take part in multidisciplinary teams entrusted with the rational exploitation of renewable resources and the conservation of the environment. The silviculturists are confident that governments will give full recognition to this unanimous expression of opinion, and will accord them commensurate responsibilities at high levels in deciding policy in integrated land-use planning, as well as its execution. Meanwhile, all concerned with the practice of forestry should intensify their efforts so that the means already made available and the responsibilities already entrusted to them continue to be fully exploited.


33. Arid zone forestry is a stubborn problem confronting foresters in the northern as well as in the southern hemisphere. Population pressure is high in dry countries, and degradation of the natural ecosystem progresses swiftly. As forest management practices and afforestation techniques are particularly difficult to work out and apply properly, research in these fields should receive increasingly greater attention and financial support by international organizations. A world-wide meeting on arid zone forestry, including problems related to irrigated plantations and the silviculture of natural forests, should be convened soon by FAO) or other international organizations concerned.

34. In view of the wastage of time and effort which the unorthodox conduct of species and provenance trials entails, the International Union of Forestry Research Organizations should pay particular attention to this problem and endeavour to issue standards for the execution of such trials. The same applies to the standardization of thinning parameters.

35. International and national forest research institutions should keep in clear perspective the need for acquiring the basic knowledge necessary to enable manmade forests in the future to contribute to meeting the demand for large-sized timber, as they already do significantly with regard to industrial wood and roundwood for domestic purposes.

36. Research and other institutions concerned should devote the necessary effort to enable the social benefits of plantation forestry to be more precisely quantified.

37. Considerably more research effort should be deployed in order to bring about a better understanding of the problems connected with the natural regeneration of tropical forests. There is urgent need for a worldwide meeting to discuss in depth the multifarious and serious problems of the development of tropical forests, and FAO should do its utmost to organize such a meeting in the very near future.

38. Recent progress in the identification and control of the source of forest seed has found expression in the setting up of seed control and certification schemes, notably by the Organisation for Economic Co-operation and Development. It is recommended that countries, even outside Europe, should consider adhering to such a scheme as this would enhance the value of the seed moving in international trade and used for afforestation work, and improve the productivity of the resulting man-made forests.

39. The need to select first promising species and then the best adapted provenances is an essential prerequisite to the execution of a soundly based afforestation programme. It is recommended that the United Nations Development Programme should examine with every consideration the request it has received for a global project on the exploration, collection, evaluation and conservation of forest gene resources.

40. The reluctance of international financing organizations to entertain applications for forest regeneration purposes should be overcome.

41. Investigations should be pursued by research institutions in close collaboration with those industries which ultimately have to put the wood to use, to improve the knowledge of the technological properties of tropical timbers, and thus enlarge their market potential.

42. When natural ecosystems are subjected to accelerated erosion, countermeasures can no longer be passive and ought to become dynamic, with resort to exotic species if need be. More generally, a clear-cut afforestation policy needs to be adopted not only for forest production purposes but also to provide future generations with the environment suited to man's requirements.

43. Fire knows no boundary and spreads havoc with no geographic discrimination. Its control is often an international concern. Funds should be made available to FAO to establish soon a forest fire technology unit. and an international commission on forest fire control should be set up, with the assistance of all interested agencies.

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